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HIP.md

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Current restrictions on HCC platform

  • Workaround for unsupported syncthreads_{count|and|or}.
    • uses temporary shared value and atomics
  • Workaround for buggy hipStreamQuery, hipStreamSynchronize.
    • introduces own queue management
    • hipStreamQuery and hipStreamSynchronize did not work in multithreaded environment
  • Workaround for missing cuStreamWaitValue32.
    • polls value each 10ms
  • device constant memory not supported yet
  • note, that printf in kernels is still not supported in HIP
  • 3D memory is currently disabled
    • missing hipMemcpy3DAsync is replaced with hipMemcpy3D though
    • exclude hipMalloc3D and hipMallocPitch when size is zero
      • otherwise they throw an Unknown Error
    • TestAccs excludes 3D specialization of Hip back-end for now
    • ... because verifyBytesSet fails in memView for 3D specialization
  • dim3 structure is not available on device (use alpaka::vec::Vec instead)
  • Constructors' attributes unified with destructors'.
    • host/device signature must match in HIP(HCC)
  • a chain of functions must also provide correct host-device signatures
    • e.g. a host function cannot be called from a host-device function
  • recompile your target when HCC linker returned the error: "File format not recognized clang-7: error: linker command failed with exit code 1"
  • if compile-error occurred, the linker still may link, but without the device code
  • AMD device architecture currently hardcoded in alpakaConfig.cmake

Compiling HIP from source

Follow this guide for installing HIP. HIP requires either nvcc or hcc to be installed on your system (see guide for further details).

  • If you want the hip binaries to be located in a directory that does not require superuser access, be sure to change the install directory of HIP by modifying the CMAKE_INSTALL_PREFIX cmake variable.
  • Also, after the installation is complete, add the following line to the .profile file in your home directory, in order to add the path to the HIP binaries to PATH: PATH=$PATH:<path_to_binaries>
git clone --recursive https://github.com/ROCm-Developer-Tools/HIP.git
cd "HIP"
mkdir -p build
cd build
cmake -DCMAKE_BUILD_TYPE="${CMAKE_BUILD_TYPE}" -DCMAKE_INSTALL_PREFIX=${YOUR_HIP_INSTALL_DIR} -DBUILD_TESTING=OFF ..
make
make install

Set the appropriate paths (edit ${YOUR_**} variables).

# HIP_PATH required by HIP tools
export HIP_PATH=${YOUR_HIP_INSTALL_DIR}
# Paths required by HIP tools
export CUDA_PATH=${YOUR_CUDA_ROOT}
# - if required, path to HCC compiler. Default /opt/rocm/hcc.
export HCC_HOME=${YOUR_HCC_ROOT}
# - if required, path to HSA include, lib. Default /opt/rocm/hsa.
export HSA_PATH=${YOUR_HSA_PATH}
# HIP binaries and libraries
export PATH=${HIP_PATH}/bin:$PATH
export LD_LIBRARY_PATH=${HIP_PATH}/lib64:${LD_LIBRARY_PATH}

Test the HIP binaries.

# calls nvcc or hcc
which hipcc
hipcc -V
which hipconfig
hipconfig -v

Verifying HIP installation

  • If PATH points to the location of the HIP binaries, the following command should list several relevant environment variables, and also the selected compiler on your system-hipconfig -f
  • Compile and run the square sample, as pointed out in the original HIP install guide.

Compiling examples with HIP back-end

As of now, the back-end has only been tested on the NVIDIA platform.

NVIDIA Platform

  • One issue in this branch of alpaka is that the host compiler flags don't propagate to the device compiler, as they do in CUDA. This is because a counterpart to the CUDA_PROPAGATE_HOST_FLAGS cmake variable has not been defined in the FindHIP.cmake file. Alpaka forwards the host compiler flags in cmake to the HIP_NVCC_FLAGS cmake variable, which also takes user-given flags. To add flags to this variable, toggle the advanced mode in ccmake.

Random Number Generator Library rocRAND for HIP back-end

rocRAND provides an interface for HIP, where the cuRAND or rocRAND API is called depending on the chosen HIP platform (can be configured with cmake in alpaka).

Clone the rocRAND repository, then build and install it:

git clone https://github.com/ROCmSoftwarePlatform/rocRAND
cd rocRAND
mkdir -p build
cd build
cmake -DCMAKE_INSTALL_PREFIX=${HIP_PATH} -DBUILD_BENCHMARK=OFF -DBUILD_TEST=OFF -DCMAKE_MODULE_PATH=${HIP_PATH}/cmake ..
make

The CMAKE_MODULE_PATH is a cmake variable for locating module finding scripts like FindHIP.cmake. The paths to the rocRAND library and include directories should be appended to the CMAKE_PREFIX_PATH variable.